Drawing-board



(No Model.)

H. HOWSON.

DRAWING BOARD- No. 340,914. Patented Apr. 27, 1886.

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the ends or on its under side, as in my im- UNITED STATES PATENT OFFICE.

HENRY HO\VSON, OF PHILADELPHIA, PENNSYLVANIA.

DRAWING-BOARD.

SPECIFICATION forming part of Letters Patent No. 340,914, dated April27, 1886 Application filed October 14, 1885.

To all whom it may concern:

Be it known that I, HENRY HOWSON, a citizen of the United States,residing in Philadelphia, Pennsylvania, have invented certainImprovements in Drawing-Boards, of which the following is aspecification.

My invention has for its object the maintenance of the edges on whichthe head of the T- square bears, perfectly true, and at right angles toeach other at all times.

In the accompanying drawings, Figure 1 is a perspective view of adrawing-board with my improvement; Fig. 2, a sectional perspective viewof a portion of the board on a larger scale, and Figs. 3, 4 and 5 viewsillustrating different ways of carrying out the invention.

A is the board,which need not be provided with the usual tongued andgrooved pieces at proved drawing-board absolute truth of the edges ofthe board itself is not essential.

1 form a recess in the upper side of the board along two of its edges,and insert in this re cess a right-angled .metal strip, B, which issecured to the board by screws 42, or in any other-suitable manner. Theedges of this strip preferably project slightly beyond the edges of theboard A, in order that any distor ion of the board caused by warpingwill not affect the edge against which the head of the T- square Dbears.

In mechanical drawing the left-hand edge b of the board is mostly used,and short vertical lines are drawn by the use of an anglestrip the baseof which bears upon the upper edge of the T-square; but when longvertical lines are to be made, the Tsquare is adjusted so that its headbears against the edge I), as shown by dotted lines in Fig. 1.

In boards as at present made much care and skill are necessaryin makingthe board,in order that the edges 1) b shall be perfectly true or atright angles to each other, and the maintenance of the edges inthiscondition demands constant attention; but with my improvement a commonboard can be used, for, as the strip B is composed of one piece of metal(prefer- Serial No. 179,988. (No model.)

ably steel) and is made properly true in the first place, it will retainits truth irrespective of the warping of the board. I prefer to grad- Uuate the inner edges of the strip B, as this is considerable of an aidto the draftsman.

In Fig. 3 I have shown the strip B as provided with an edge flange, f,so as to form a more extended bearing for the head of the T- square.

The board may, if desired, be provided with two right-angled strips ofmetal, as shown in Fig. 4. so as to present a metallic edge all around.

In Fig. 5 I have shown the strip 13 extending along the three edges 1) bI) of the board; but I prefer the use of the single right-angled stripshown in Fig. 1.

I claim as my invention 1. The combination, with a drawing-board, of aright-angled metallic strip permanently attached to the upper surface ofsaid board, substantially flush with the same, extending along two ormore of its edges and forming the bearing for a T-square head, allsubstantially as specified.

2. The combination, with a drawing-board, of a right-angled metallicstrip permanently attached to the upper surface of said board,presenting a face substantially flush with the same and projectingbeyond the edges of the board, forming the bearing for a T- square head,all substantially as set forth.

8. The combination, with a drawing-board, of a right-angled metallicstrip permanently attached to the upper surface of said board,presenting a face substantially flush with the same,and having adownwardly-projectiug flange, to form a more extended bearing for thehead of the T-square, all substantially as specified.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

HENRY HOWSON.

Witnesses:

XVILLIAM F. DAVIS, HARRY SMITH.

